1. Field of the Invention
The invention relates generally to a storage apparatus and method of managing storage data using the same, and particularly to a remote copy technique for storage data using a journal between storage apparatuses having data encryption/decryption functions.
2. Description of Related Art
In order to prevent data loss caused by failures that occur in a storage apparatus in a computer system, data stored in a logical volume in the storage apparatus is normally backed up in another logical volume in a remote storage apparatus that is redundantly structured. For example, “remote copy” (or “remote mirroring”) is known as a technique for backing up data in logical volumes. Specifically, in the remote copy, data is backed up by defining a logical volume in a primary storage apparatus (primary logical volume) and a logical volume in a secondary storage apparatus (secondary logical volume) as a pair of volumes, and copying data in the primary logical volume to the secondary logical volume, either as it is written to the primary logical volume, or at a later point in time. With such an arrangement, even if a failure occurs in the primary storage apparatus, the secondary storage apparatus can take over I/O access requests received from an application in a host computer.
Also, “journaling” is a well-known technique for increasing the speed of data backup/data restoration. In journaling, upon receipt of a data write request (command), data to be written and its meta data (e.g., time) is stored as a journal. In general, a logical volume for storing journals is referred to as a journal volume.
Document 1 (JP2005-18506 A) discloses a storage system using a journaling technique in the remote copy. Specifically, in reference 1, when a first storage system receives a write command for data in a certain one of its volumes, the first storage system updates the data in the volume, creates a journal by adding the receipt time to the write data, and transfers the created journal to a second storage system. The second storage system updates the data in its own volume based on the transferred journal. Accordingly, replication of the volume in the first storage system is created in the second storage system.
In terms of data security, data is often encrypted when it is stored in a storage apparatus. However, in old encrypted data that has been kept for a long time after the encryption, the encryption key and encryption algorithm used in the encryption might be weakened. In particular, since data of a certain type, such as e-mail data, is required to be stored for a long time due to government regulations, etc., these days, a technique for safely storing data for a long time is required.
Document 2 (JP2005-303981 A) discloses a storage system that encrypts data when storing it in order to ensure the confidentiality of the data. In addition, encrypted data is re-encrypted in accordance with a new and more robust encryption standard set in the storage system in reference 2. With such an arrangement, problems relating to the weakening of encryption keys or encryption algorithms can be avoided and data can be safely stored for a long time with its confidentiality intact.
In terms of data security, when data is encrypted or re-encrypted, since encryption/re-encryption processing applies a large load on a processor, system performance deteriorates. However, in the remote copy, a storage system is required to maintain high response performance to a write request from a host computer. Under such circumstances, a storage system that performs encryption/re-encryption causing a large processing load during remote copy has not been proposed.
In particular, the above storage system disclosed in cited document 2, in which the entire volume is re-encrypted and the load on the processor is accordingly large, could not be applied to a storage system using the remote copy technique.
It is therefore an object of this invention to propose a storage system and a data management method capable of performing efficient data backup while ensuring data security.
More specifically, the above object of this invention is to remote-copy data that requires encryption/decryption processing without lowering system performance.
In addition, the above object of this invention is to, even if an encryption key for a logical volume storing data has been updated, efficiently store encrypted data encrypted with the up-to-date encryption key in the logical volume, and also efficiently read the encrypted data from the logical volume and decrypt the encrypted data.